如何使用字符串值对JSON数组进行排序？

Question

我有一个简单的JSON数组：

_bb jsonb =

[
  {
    "so": "1",
    "mdl": "Testing",
    "pos": "Top"
  },
  {
    "so": "1",
    "mdl": "FlashSale",
    "pos": "Bottom"
  },
  {
    "so": "1",
    "mdl": "Testing",
    "pos": "Top"
  }
]

我想要实现的目标：

[
  {
    "so": "1",
    "mdl": "Testing",
    "pos": "Top"
  },
  {
    "so": "1",
    "mdl": "Testing",
    "pos": "Top"
  },
  {
    "so": "1",
    "mdl": "FlashSale",
    "pos": "Bottom"
  }
]

我试过了

Select _bb  into _test  ORDER BY _bb->>'pos' ASC  ;

我实现的是所有pos =“Top”是JSON中的第一个，而所有的“Bottom”都是最后一个。 有没有办法在Postgres实现这一目标？

Answer 1

with j(_bb) as (values('[
  {
    "so": "1",
    "mdl": "Testing",
    "pos": "Top"
  },
  {
    "so": "1",
    "mdl": "FlashSale",
    "pos": "Bottom"
  },
  {
    "so": "1",
    "mdl": "Testing",
    "pos": "Top"
  }
]'::jsonb))
, ord(o,v) as (values(1,'Top'),(2,'Bottom'))
, un as (select *,jsonb_array_elements(_bb) i from j)
select jsonb_agg(i order by o) from un
join ord on v=i->>'pos'
;

结果如下：

[
  {
    "so": "1",
    "mdl": "Testing",
    "pos": "Top"
  },
  {
    "so": "1",
    "mdl": "Testing",
    "pos": "Top"
  },
  {
    "so": "1",
    "mdl": "FlashSale",
    "pos": "Bottom"
  }
]

不用说你必须为所有值建立订单矩阵，例如：

, ord(o,v) as (values(1,'Top'),(2,'Middle'),(3,'Bottom'))

http://rextester.com/ZNDQ97753